[MHml] Ackermann for cats : pdf file

[multihulls at steamradio.com]

4-3-01 Tom Speer wrote:

> > F27 Twinrudders6.jpg:
>  > My next boat was a Farrier F27, and I found the original rudder totally
>  > inadequate, so I built a new rudder for that boat, again using the "
> reverse
>  > Ackermann" design. Again very successful.
>  
>  Interesting!  Why did you go with two rudders instead of a single
>  larger rudder?  And are those rudders fixed or retractable?

I used 2 rudders for shallow draft, AND I could put a gearing in the system.
10 degrees of helm gave 16 degrees on the rudder blades.
The original F27 helm moved through an arc of 2 metres, so I couldn't stay 
seated in one place while manoeuvring.  With the geared rudder system I can 
stay seated.
Rudders are daggerboard-type, fully retractable, and half up you still can 
steer the boat while the outboard is the deepest point of the boat.  There 
are lots, miles and miles, of shallow waters around here.

>  > 
>  > rev_ack.gif:
>  > Here is a schema off the "reverse Ackermann" design.  I think it explains
>  > itself.
>  > 
>  
>  This looks to be a good way to implement auxilliary rudders on
>  the amas, off the central rudder on a tri.

Yes, and there is actually a large trimaran (Aquarius) here in the 
Netherlands using a similar system, with no rudder on the main hull.
  
>  Cheers,
>  
>  -- 
>  Tom Speer

BTW:  I could download your PDF-file Tom, but am getting error messages from 
Acrobat, so your file isn't readable.

Regards,   Han